By Sarah Turner

LONDON (Dow Jones)--Helped by a late flurry, British shares extended a winning streak to eight sessions, as earnings season continued to impress traders.

Having traded flat to lower for much of the session, well-received U.S. housing data also helped drag the U.K. FTSE 100 index to a positive close, with the top index rising 12.6 points, or 0.3%, to 4,493.73.

"The FTSE 100 is currently enjoying something of a winning streak as companies seem to have consistently posted profits that have beaten analyst' expectations," said David Jones, chief market strategist at IG Index.

Drug maker GlaxoSmithKline (GSK) was in that camp, as Europe's largest drugmaker said its second-quarter profit rose 12%, as revenue rose 15% to 6.75 billion pounds. Excluding restructuring charges, adjusted earnings per share rose 14% to 31 pence, which was above analyst estimates of 30 pence.

Glaxo shares edged 0.6% lower, but rival drugmakers advanced. Shire rose 4%, and AstraZeneca added 1.2%.

Imperial Tobacco rose 2.7% following rival Altria's topping of expectations.

On the downside, mining giant BHP Billiton (BHP) traded down 1.8%.

The firm reported a 10% fall in iron-ore output in the fourth quarter ended in June, and a full-year figure below previous guidance.

BHP Billiton also said in a statement that "underlying demand trends are still being masked by de-stock and stocking activities."

"We believe the shares are too far ahead of events, especially given scope for mine restart," said analysts at Evolution Securities, referring to the potential for currently shut mines across the industry to reopen.

Other mineral extractors under pressure included Lonmin , down 3.2%, and Kazakhmys , down 2.1%.

Banks were mostly lower, with Barclays (BCS) down 3.1% to lose ground for a second day.

Analysts at J.P. Morgan said in a note out Tuesday that they believe the bank's Barclays Capital unit will need three times its current level of economic capital by 2010.

"Despite the sale of BGI, we see a capital deficit of 12.8 billion pounds," the broker said.

It also believes Royal Bank of Scotland will need more capital. "[We] now see a capital deficit of 8.5 billion pounds, compared to 2 billion pounds previously," the broker said. RBS shares fell 0.3%.

The analysts believe there will be a meaningful impact from regulatory changes to market risk.

"We foresee a 30% to 100% increase in sector capital requirements as a result of incremental risk charge; stressed value-at-risk and higher 'quality' of capital," they said.

-Sarah Turner; 415-439-6400; AskNewswires@dowjones.com